NVD / CVE Program· CNA Linux

CVE-2024-39463: 9p: add missing locking around taking dentry fid list

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Linux Linux 3bb6763a8319170c2d41c4232c8e7e4c37dcacfb, c898afdc15645efb555acb6d85b484eb40a45409, cb299cdba09f46f090b843d78ba26b667d50a456.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 3bb6763a8319170c2d41c4232c8e7e4c37dcacfb, c898afdc15645efb555acb6d85b484eb40a45409, cb299cdba09f46f090b843d78ba26b667d50a456 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: 9p: add missing locking around taking dentry fid list Fix a use-after-free on dentry's d_fsdata fid list when a thread looks up a fid through dentry while another thread unlinks it: UAF thread: refcount_t: addition on 0; use-after-free. p9_fid_get linux/./include/net/9p/client.h:262 v9fs_fid_find+0x236/0x280 linux/fs/9p/fid.c:129 v9fs_fid_lookup_with_uid linux/fs/9p/fid.c:181 v9fs_fid_lookup+0xbf/0xc20 linux/fs/9p/fid.c:314 v9fs_vfs_getattr_dotl+0xf9/0x360 linux/fs/9p/vfs_inode_dotl.c:400 vfs_statx+0xdd/0x4d0 linux/fs/stat.c:248 Freed by: p9_fid_destroy (inlined) p9_client_clunk+0xb0/0xe0 linux/net/9p/client.c:1456 p9_fid_put linux/./include/net/9p/client.h:278 v9fs_dentry_release+0xb5/0x140 linux/fs/9p/vfs_dentry.c:55 v9fs_remove+0x38f/0x620 linux/fs/9p/vfs_inode.c:518 vfs_unlink+0x29a/0x810 linux/fs/namei.c:4335 The problem is that d_fsdata was not accessed under d_lock, because d_release() normally is only called once the dentry is otherwise no longer accessible but since we also call it explicitly in v9fs_remove that lock is required: move the hlist out of the dentry under lock then unref its fids once they are no longer accessible.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2024-07928

Published: Jun 25, 2024
Updated: Aug 5, 2026
EPSS: 0.2% · 16th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.8
CNA · Linux: 7.8; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

linux linux kernel5.11 and later · before 5.15.168
linux linux kernel5.16 and later · before 6.1.94
linux linux kernel6.2 and later · before 6.6.34
linux linux kernel6.7 and later · before 6.9.5
linux linux kernel6.10

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

Linux Linux
- 5.11affected
- 154372e67d4053e56591245eb413686621941333 and later · before 3bb6763a8319170c2d41c4232c8e7e4c37dcacfbaffected · git
- 154372e67d4053e56591245eb413686621941333 and later · before cb299cdba09f46f090b843d78ba26b667d50a456affected · git
- 154372e67d4053e56591245eb413686621941333 and later · before f0c5c944c6d8614c19e6e9a97fd2011dcd30e8f5affected · git
- 154372e67d4053e56591245eb413686621941333 and later · before fe17ebf22feb4ad7094d597526d558a49aac92b4affected · git
- 154372e67d4053e56591245eb413686621941333 and later · before c898afdc15645efb555acb6d85b484eb40a45409affected · git
- before 5.11not affected · semver
- 5.15.168 and later · up to and including 5.15.*not affected · semver
- 6.1.94 and later · up to and including 6.1.*not affected · semver
- 6.6.34 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.94-1	6.1.94-1
Debian:13	linux	before 6.9.7-1	6.9.7-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2024-39461Jun 25, 2024 · clk: bcm: rpi: Assign ->num before accessing ->hws
22Monitor
← EarlierCVE-2024-39462Jun 25, 2024 · clk: bcm: dvp: Assign ->num before accessing ->hws
39Monitor
Later →CVE-2024-39464Jun 25, 2024 · media: v4l: async: Fix notifier list entry init
22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Linux Linux	3bb6763a8319170c2d41c4232c8e7e4c37dcacfb	Vendor (CNA)
Linux Linux	c898afdc15645efb555acb6d85b484eb40a45409	Vendor (CNA)
Linux Linux	cb299cdba09f46f090b843d78ba26b667d50a456	Vendor (CNA)
Linux Linux	f0c5c944c6d8614c19e6e9a97fd2011dcd30e8f5	Vendor (CNA)
Linux Linux	fe17ebf22feb4ad7094d597526d558a49aac92b4	Vendor (CNA)
debian:linux	6.1.94-1 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-24-0790 · Jun 26, 2024(Linux Kernel Güncellemesi)

All national notices →

Technical details

Attack conditions

Someone with local access to the system can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:08 PM UTC

For records you follow, these changes also arrive as notifications. →

References

git.kernel.org/stable/c/3bb6763a8319170c2d41c4232c8e7e4c37dcacfb

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records